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Apyifi 22, 1930. F. FISCHER ET AL ELECTRICAL SPARK CONTROL FOR BURNERSFiled July 6, 192a 2'Shet-Sheet 1 Fig. I

INVENTOR QMZMW Apxifi 22, 1939.. F. FISCHER ET AL 1,7555% ELECTRICALSPARK CONTROL FOR BURNERS Filed July 6, 192a 2 Sheets-Sheet 2 PatentedApr. 22, l33

cranes FRANK FISCHER, OFRYE, NEW YORK, AND ARNOLD E. VAN FELT, FINTERLAKEN, NEW JERSEY, ASSIGNORS T0 GRANT 01L BURNER CORPGRATIGN, 0FWILMINGTON, DELAWARE, A CORPORATION OF DELAWARE ELECTRICAL SPARK CQNTBOLFOR Application filed July 6, 1926. Serial No. 120,855.

Our invention relates to safety ignition means for burners, and pertainsparticularly to an arrangement whereby an electrical spark of suitableintensity must be present in order to permit operation of the burner.

It is a comparatively simple matter to prevent operation of a burnerunless a current is flowing through the ignition circuit, but such anarrangement would not shutdown the burner in the case of a short circuitof the spark gap; or in case a thin spark (of insufi'icient intensity toignite the burner) were obtained.

One of the objects of our invention is to prevent injecting fuel intothe combustion chamber unless an ignition spark of required intensity ispresent at the electrodes.

Another object is to obtain a suitable ignition spark prior to thestarting of the fuelsupply motor.

Another object is to shut down the burner in case the ignition sparkshould fail while the burner is in operation.

Other objects will hereinafter appear.

The nature and scope of our invention are more thoroughly explained inthe following description taken in connection with the accompanyingdrawings forming part of this specification, in Which:

Fig. I is a diagram of our spark control circuit in which two relays,actuated by different voltages, are connected in parallel across thespark-gap so as to open and close the main motor circuit.

is a diagram similar to Fig. 1, exonly one relay instead of two iscmployedthe armature of this relay having three positions to which it ismoved in accordance with the magnitude of the impressed voltage.

Fig. lll 1s a circuit similar to Fig. H but having a relay with a singlecontact armature, and receiving its current from a secondary transformercoil, the primary coil of which forms an inductive resistance which isconnected in series with a condenser across the spark gap.

Fig. IV shows another means of closing or opening the motor circuitthrough the presence or absence respectively, of a sparkproducingpotential across the electrodes. In this arrangement two relays and aresistance are employedone relay being connected in parallel across thespark gap, and the other relay and a resistance in series with eachother being connected in a shunt circuit around the motor.

Similar numerals refer to similar parts in all of the figures, in which:

1 and 2 are alternating current power leads, 3 is a motor, 4 and 5 areelectrodes separated by spark-gap 6. 7 and 8 are wires connecting theignitiontransformer primary coil 9 in parallel across leads 1 and 2 whenswitch 10 is closed. Switch 10 represents either a manually operatedswitch or any type of thermostat or automatic switch for closing andopening the circuit.

In the adaptation shown, the air and oil pump 16 is driven by motor 3and discharges a combustible mixture of oil and air through conduit 17and nozzle 18 into the firebox of the furnace.

The ignition transformer secondary coil 11 is connected by means ofwires 12 and 13 to said electrodes 4 and 5. 14 and 15 are wiresconnecting relay-coil 19 directly in parallel with the secondary of theignition trans,- former as shown in Figs. ll, H and IV. The slightdifference in Fig. Hit will be explained later. 20 is the armatureactuated by relaycoil 19, and 21 is a contact point with which 20contacts to connect armature 20 to one of the main power-leads 1 or 2.

22, in Figs. 1 and 1V, represent additional relays having armatures 23and contact points 24 arranged in series with the motor circuit.

25 (Figs. H and 1V) is a spring mounted on rigid support 26. Spring 25is of such height as not to contact with the extension arm 27 ofarmature 20 when coil 19 is deenergized, or until armature 20 reachesits central position indicated by point 21 in Fig. 11 and by centralposition indicated by dotted 4 lines 33 in Fig. IV. When armature 20 ispulled to its extreme upward position spring is making contact withpoint 32 or point In Fig. III relay-coil 19 is connected in parallelwith the secondary of a special transformer, the primary 29 of which isconnected in series with condenser 28. Wires 14 and 15 in this figureconvey energy from wires 13 and 12 to primary 29 and condenser 28 andindirectly through secondary 30 to relay-coil 19, instead of directly asin Figs. I, II and IV.

The operation of our electrical spark control for burners is as follows:

The power current is always presumed to be on lines 1 and 2.

When the control switch 10 is closed the primary coil 9 of ignitiontransformer is energized. This energizes the high-tension secondary coil11 producing a voltage of say 10,000 volts which normally causes a sparkto jump across the spark gap 6 between the electrodes 4 and 5.

After a suitable ignition spark is produced and a current flowestablished in the secondary circuit, the initial voltage, which wasrequired to break down the gap resistance, is reduced by virtue of thevoltage drop within the transformer. When the proper spark is passingthrough the electrodes there exists a potential difi'erence betweenwires 12 and 13; and relay-coil 19 is energized by said potentialdifference. Relay-coil 19 is so wound as to lift armature 20 when thusenergized, and thereby to bring about connection of motor 3 across themain power-leads 1 and 2.

Referring to Fig. I for illustration, relaycoil 19 is designed tooperate only from a source of supply, the potential difference of whichis equal to the potential difference existing across the spark-gap whentheproper spark is flowing.

Relay-coil 22 in Fig. I isdesigned to 0perate from a source of supply,the potential difference of which is very high, as for instance, fromthe secondary of the'ignition transformer when the spark-gap-is toowidely spaced and hence offers a resistance too great for the availablepotential to break down. A continued condition as just noted, willresult in the relay 22 being actuated and thereby breaking the mainmotor circuit at contact point 24. Armature 23 is therefore in contactwith point 24 under all conditions except when the otential differencebetween wires be if a spark were passing between electrodes -4and5.

It should be noted that if electrodes 4 and 5 'are short-circuited, thepotential difference between Wires 12 and 13 drops to practically zero.The potential difference between wires 12 and 13 increases from zero toa maximum (depending upon the design of the transformer) as gap 6,between electrodes 4 and 5, is increased. Armature 20 is therefore onlyin contact with point 21 when a definite minimum potential between 12and 13 has been passed, and armature 20 is held in contact with point 21for all potentials existing between 12 and 13 above a definite fixedminimum value.

If there exists no potential difference be- If an excessive potential(anything above a predetermined limit) exists between 12 and 13, circuitof motor 3, while closed at contact points of relay 19, will be open atcontact points of relay 22.

Fig. II shows an arrangement with a single relay 19 connected to wires12 and 13, said wires being connected to the secondary of the ignitiontransformer. This relay is designed to respond to two differentpotentials. The first potential is that existing across wires 12 and 13when a spark of the proper intensity is passing between electrodes 4 and5 across gap 6. When responding to such a potential the armature of 20is lifted up to its central position, determined by initial contact withspring 25, thereby making contact with point 21 and thus completing thecircuit of motor 3.

The second potential to which relay 19 is responsive is that existingbetween wires 12 and 13 when the ignition transformer is energized, butwhen electrodes 4 and 5 are so widely spaced that there is notsufiicient current flow across gap 6 to establish a spark suitable forignition purposes. When relaycoil 19 is subjected to this secondpotential, armature 20 is raised to its extreme position, as shown bydotted line 33, thereby opening main circuit of motor 3.

In Fig. III a single relay-coil 19 is used which obtains its energy fromthe secondary 30 of a special transformer, primary 29 of which isconnected in series with a suitable condenser 28, both of which latterare connected by wires 14 and 15 to wires 13 and 12. 12 and 13 iconsiderably higher than it would The design of primary coil 29 andcondenser 28 are such as to preclude any current flow through themselveswhen subject to a potential of a frequency of approximately 60 cycles.However, 29 and 28 are responsive to a frequency considerably higherthan 60 cycles and, when subject to said higher frequency, inducesufiicient current in secondary coil 30 to energize relay-coil 19, thusclosing motor circuit 3 through armature 20 at point 21.

An inspection of Fig. III will show that the circuitcomprised ofcondenser 28, wire 15, wire 12, electrode 5, spark-gap 6, electrode 4,wire 14 and coil 29, will oscillate at a much higher frequency than 60cycles when an ignition-spark is present at the gap. lhe above circuitand relay 19 and secondary coil 30 have been so designed as to beresponsive only to a frequency much higher than 60 cycles. This higherfrequency'is only present when a proper spark is flowing betweenelectrodes ii and 5 across gap 6, hence relay 19 and consequently motor?are in fact only responsive when a proper spark is flowing across gap 6.

Relay-coil 19 15 only one of the means we have in mind for utilizing theenergy from the spark circuit to close some of this circuit of motor 3.For instance, a vacuum or gas filled tube could well be adapted toreceive the energy and act in a similar capacity to relay 19; or, such atube could be arranged to receive the energy from the ignition means andactuate a second relay or a series of relays which would enable us tohandle a motor of any capacity.

In ig. IV a non-inductive resistance 29 with relay-coil 22 in series,are connected across the main power circuit 1 and 2 when switch 10 isclosed. Relay-coil 22 is efiectively shunted out of the circuit whenarmature 20 contacts with point 21 or with point 32, but relay-coil 22is not shunted out and is therefore energized when armature 20 is in itscentral position at 33, which occurs only when relay-coil 19 isenergized by the suitable potential which is present on wires 12 and 13when a proper ignition spark is passing across gap 6 between electrodes4 and 5. It will be seen that when relay-coil 19 is not energized,relay-coil 22 is shunted out, and likewise when relay-coil 19 isenergized to an excessive value relay-coil 22 is again shunted out. litshould be borne in mind that the circuit to motor 3 is open at all timesunless relay-coil 22 is efiectively energized.

Having described our invention, what we claim and desire to secure byLetters Patent 1s:

1. In a burner ignition device having a controlled circuit, a highvoltage controlling circuit energizedfrom a substantially con stantpotential, the controlling circuit having a pair of spaced electrodesforming a spark gap for igniting the burner, relay means for closing thecontrolled circuit when an ignition spark is present at the spark-gapand the controlled circuit when said igark is absent, and a shuntcircuit e spark-gap for operating the relay opening nition s around tmeans.

2. In a control mechanism for burners, a power circuit, a relay operatedswitch for opening and closing the power circuit, a transformersecondary circuit having a spark gap for igniting the burner, a shuntcircuit connected around the spark gap, and means energized b said shuntcircuit for closing the relay switch when the precise ignition-sparkproducing current flows across the gap.

. FRANK FISCHER.

ARNOLD F. VAN FELT.

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